Abstract
Rock fracture mechanics has been widely applied to blasting, hydraulic fracturing, mechanical fragmentation, rock slope analysis, geophysics, earthquake mechanics and many other science and technology fields. Development of failure in brittle materials is associated with microcracks, which release energy in the form of elastic waves called acoustic emissions. In the present study, acoustic emission (AE) measurements were carried out during cracked chevron notched Brazilian disc (CCNBD) tests on Nestos marble specimens. The fracture toughness of different modes of loading (mode-I and –II) is calculated and the results are discussed in conjunction with the AE parameters.
Highlights
Fracture mechanics can be applied to many engineering fields including civil and mining engineering, where drilling, excavation, explosion and cutting of rocks are closely related to the strength, stability and fracture of rock materials and structures
This study focuses on the correlation between the acoustic emission (AE) signals and the diametrically applied load during cracked chevron notched Brazilian disc (CCNBD) tests
SRock fracture toughness for pure mode I ix CCNBD tests were performed for the determination of mode I fracture toughness (Fig 8)
Summary
Fracture mechanics can be applied to many engineering fields including civil and mining engineering, where drilling, excavation, explosion and cutting of rocks are closely related to the strength, stability and fracture of rock materials and structures. Among many different testing methods for rock fracture toughness, the International Society for Rock Mechanics (ISRM) suggests the Chevron Bend (CB) and the Short Rod (SR) specimens [1]. The introduction of the CSTBD and CCNBD tests, allows the determination of rock fracture toughness under mode I (opening mode), mode II (in plane shear mode) and mixed mode I-II loading cases. Both of these tests configurations show great potential for current and future applications and overcome the disadvantages of the CB and SR specimens. The International Society for Rock Mechanics [6] suggested the cracked chevron notched Brazilian disc (CCNBD) for determining the mode I fracture toughness of rock. The acoustic emission activity was monitored using piezoelectric acoustic emission sensors, and the potential for accurate prediction of the fracture load based on acoustic emission data is investigated
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